1. Field of the Invention
The present invention relates to an image generating apparatus, an image generating method, an image display medium, and a computer readable recording medium, and, more particularly, to an image generating apparatus, an image generating method, an image display medium, and a computer readable recording medium which are fit for prohibition of information leak.
2. Description of the Related Art
The advanced copying technology can create copies which are difficult to be distinguished from their originals. Unexamined Japanese Patent Application KOKAI Publication No. 2005-295519 and Unexamined Japanese Patent Application KOKAI Publication No. 2001-324898, for example, disclose techniques of discriminating a copy from an original using a background tint pattern to determine whether a subject is a copy.
In the invention described in Unexamined Japanese Patent Application KOKAI Publication No. 2005-295519, as shown in FIG. 1 thereof, a background tint for alteration or manipulation verification and a background tint for detecting illegal duplication are comprised of plural kinds of dots, and a dot image for detection is generated according to an image to be protected by the background tints. Then, the dot image for detection is superimposed on the image to be protected, thereby yielding a superimposed image. This can ensure alteration verification and can permit a copy, if duplicated from an original, to be visually discriminated.
The invention described in Unexamined Japanese Patent Application KOKAI Publication No. 2001-324898, as illustrated in FIG. 13 thereof, generates a security background tint comprising a basic security background tint which disappears at the time of duplication by a copying machine and a concealed security background tint which is clearly duplicated at the time of duplication by the copying machine. The security background tint is printed together with a print image. As a result, when the printout is copied, the background tint disappears or stands out, thus making it possible to discriminate the original from a copy.
From the viewpoint of privacy protection, it is emphasized to protect personal information. Particularly, the advancement of copying technology makes printing and duplication easier, making it necessary to be cautious about information security. Although the techniques described in the aforementioned publications can discriminate a copy from an original and alteration of the contents thereof, the techniques are not effective in suppressing information leak for an image and/or characters on a copy can be viewed.
Accordingly, it is an object of the present invention to provide an image generating apparatus, an image generating method, an image display medium, and a computer readable recording medium which suppress image-based leakage of information.